Conversion and coking of hydrocarbon oils



Dec. 5, 1939. J. D. SEGUY CONVERSION AND COKING OF- HYDROCARBON OILS Filed March 22, 1937 FRACTIONATOR VAPORIZING OR CONDEN INVENTOR JEAN DELATTRE SEGUY FURNACE FURNACE TOPPING COLUMN FURNACE 7 Y E N w W A Patented Dec. 5, 1939 UNITED STATES PATENT OFFICE CONVERSION AND COKING OF HYDROOAR- BON OILS Application March 22, 1937, Serial No. 132,189

1 Claim.

This is a continuation-in-part of my co-pending application Serial No. 630,858, filed August 29, 1932.

This invention particularly refers to an improved process and apparatus for the simultaneous topping and cracking of hydrocarbon oil, accompanied by reduction of the residual conversion products to coke at reduced pressure.

One of the primary objects of the invention is to provide a simple and economical process wherein a raw oil charging stock, which may comprise a crude oil or any other hydrocarbon oil of relatively wide boiling range is treated in a sequence co-related and interdependent steps comprising distillation or topping of the charging stock, recovery of its desired low-boiling fractions, cracking of its higher boiling components, together with intermediate liquid products of the operation, and coking of the heavy residual liquid products, whereby to produce, primarily, high yields of gasoline and a solid residue such as good quality coke.

Another object of this invention is to provide a simple and effective method and means whereby heavy pitch-like and/or tarry materials evolved from the hot conversion products undergoing coking and carried over from the coking zone with the vaporous products of the coking operation are separated from the lighter components of said vapors, prior to fractionation of the latter for the formation of reflux condensate, and returned to the coking step together with the other heavy oils subjected to coking. This feature of the invention provides a relatively clean reflux condensate which is substantially free of undesirable high coke-forming components and which may be advantageously further cracked in the same heating coil to which the initial cracking stock is supplied without the danger of encountering excessive coke formation and deposi tion in this zone.

Other objects and advantages of the invention will be apparent from the following more specific description of the process.

In one specific embodiment, the present invention comprises heating a hydrocarbon oil to effect its substantial vaporization and introducing it into a vaporizing or topping chamber wherein its relatively light and heavy components are separated, subjecting said heavy components, which remain unvaporized in the topping chamber, to conversion temperature at super-atmospheric pressure in a heating coil and, when desired, to continued conversion in a reaction chamber, introducing the heated conversion products into a vaporizing chamber wherein the residual liquid and vaporous conversion products are separated, withdrawing the residual liquid from said separating zone, subjecting it to further heating and then introducing it into a coking chamber wherein it is reduced to coke, combining vaporous products of the topping, cracking and coking operations and subjecting the commingled said vapors to fractionation, cooling, condensing, and collecting the desired light overhead product and subjecting reflux condensate resulting from said fractionation to further conversion together with the topped raw oil or, optionally, supplying it for further conversion to the same heating coil to which the residual liquid conversion products are supplied.

The attached diagrammatic drawing illustrates one specific form of apparatus in which theprocess of the invention may be conducted. The raw oil charging stock to be treated, which may comprise crude oil or any other hydrocarbon oil of relatively wide boiling range, is supplied through line I and valve 2 to pump 3, from which it is fed through line 4 and valve 5 to heating coil 6. Heating coil 6 is located in furnace l of any suitable form by means of which the oil is heated under any desired pressure conditions to the temperature required for a substantial subsequent vaporization in vaporizing or topping chamber 8 to which it is supplied through line 9 and.

valve I0.

Topping chamber 8 is preferably maintained at substantially atmospheric pressure or low superatmospheric pressure, and the heated oil supplied thereto is separated into light and heavy fractions, the light fraction being removed as vapors while the heavy fraction, comprising the raw oil which remains unvaporized in chamber 8, is removed therefrom through line H and valve I2 to pump l3 by means of which it is supplied through line l4 and valve IE to heating coil l6. Heating coil I6 is supplied with heat from furnace I! of any suitable form, whereby the topped raw oil is heated to the desired conversion temperature, preferably at substantial superatmospheric pressure, and may then be discharged through line l8 and valve I 9 into separating chamber 20.

When continued conversion time is desired for the heated oil leaving coil l6, it may be diverted from line l8 through line 2| and valve 22 into reaction chamber 23, which is preferably also maintained at substantially superatmospheric pressure by means of which the heated oil from heating coil I6, and particularlyits vaporous components, are subjected to continued conversion time, both vaporous and liquid conversion products being withdrawn from the lower portion of chamber 23 through line 24 and valve 25 into line I8, passing therethrough into chamber 20.

Separating chamber 20, as here illustrated, comprises the lower portion of fractionatingcolumn 26, being separated from the upper or fractionating portion of the column by means of a suitable partition 21, through which vapors from the separating zone may pass and upon which reflux condensate resulting from fractionation may collect. I

Residual liquid is separated from the vaporous conversion products in chamber 20 and is withdrawn from the lower portion of this zone through line 28 and valve 29 to pump 30 by means of which it is fed through line 3| and valve 32 to heating coil 33, wherein it is heated by means of heat supplied from a furnace 34, of any suitable form, to a temperature sufiicient to effect further conversion and subsequent coking of the residual oil. The heated products pass from heating coil 33 through line 35 and may be discharged through line 36 and valve 35 into coking chamber 38, or through line 36' and valve 31 into coking chamber 38'.

Coking chambers 38 and 38 are similar zones in which the residual liquid conversion products of the process are reduced to substantially dry coke. It will be understood that one or any number of a plurality of such zones may be employed, although two are illustrated in the drawing, a

plurality being preferred and being operated either alternately or simultaneously, in order to provide additional space for the accumulation of coke. Chambers 38 and 38' are provided with drain lines 58 and 58, respectively, controlled by the respective valves 59 and 59. These lines may also be utilized as a means of introducing steam, water, or other suitable cooling medium into a chamber which has been substantially filled with coke and isolated from the system, to hasten its cooling and facilitate cleaning and preparation of the chamber for further operation. The coking chambers are preferably operated at substantially atmospheric or low superatmospheric pressure although substantial superatmospheric pressures up to several hundred pounds per square inch may be employed, when desired Vaporous products are removed through linefill and valve iii from chamber 38 and from chamber 38' through line 50 and valve 6 l passing through line 62 and valve 63 to chamber 20 for further treatment, together with the heated conversion products from heating coil 15 or chamber 23, as the case may be.

Heavy tar and pitch-like materials carried over with the vapors from the coking chambers are separated therefrom in chamber 23 prior to their fractionation for the formation of reflux condensate, these heavy materials being thereby commingled with said residual liquid in chamber 20 and supplied therewith to further treatment in heating coil 33 and the coking chambers.

Vaporous conversion products from heating coil ll or chamber 23 and vapors from coking zones 38 and/or 38' pass from chamber 20 into the upper or fractionating portion of column 23 wherein they commingle with the vapors from topping chamber 8, which are supplied to this zone through line 39 and valve 43, the commingling vapors being subjected to fractionation. The heavy components of thecommingled vapors, boiling above the desired end-boiling point of the final light distillate product of the system, are condensed as reflux condensate in the fractionator, from which they are withdrawn through line 4| and valve 42 to pump 43 from which it may pass, all or in part, through line 44, line 46 and valve 41 to heating coil It for further conversion.

It is sometimes desirable depending primarily upon the nature of the charging stock employed and specific conditions of temperature, pressure and conversion time employed in various steps of the process, to commingle a regulated quantity of the reflux condensate formed in fractionator 25 with the residual liquid supplied to heating coil 33. This may be accomplished by passing all or regulated'quantities of the reflux condensate supplied to pump 43 therefrom through valve 45 in line 44 into line 3| and thence to heating coil 33.

Fractionated vapors of the desired end-boiling point are removed from the upper portion of fractionator 26 through line 48 and valve 49 and are subjected to condensation and cooling in condenser 50, from which the resulting distillate and uncondensable gas pass through line and valve 52 to be collected in receiver 53.

Uncondensable gas may be released from the receiver to storage or to any desired further treatment through line 54 and valve 55. Distillate may be withdrawn from the receiver to storage or to any desired further treatment through line 56 and valve 51.

The temperature to which the raw oil charging stock is heated, prior to its introduction into the topping chamber will vary, depending upon the nature of the charging stock and the pressure conditions employed in the heating coil, between 400 and 700 F., for example, and said pressure conditions, may range, for example, from substantially atmospheric to 200 pounds, or more, per square inch, in the heating coil, preferably with substantially atmospheric or a superatmospheric pressure below 100 pounds, or thereabouts, per square inch in the topping chamber.

Conversion conditions to which the topped raw oil charging stock is subjected, measured at the outlet of the heating coil to which it is supplied, may range, for example, from 850-950 F., preferably with a superatmospheric pressure at this point in the system of from 100-500 pounds, or more, per square inch. Pressure within substantially this same range may be utilized in the high pressure reaction chamber, when such a zone is employed, while the separating chamber and succeeding fractionating, condensing, and collecting portions of the system are preferably operated at a reduced pressure which may range from 100 pounds, or thereabouts, per square inch, down to substantially atmospheric pressure.

Conversion conditions employed at the outlet of the heating coil to which the residual oil is supplied will vary, depending upon the character of the residual oil and the nature of the reflux condensate, if any, supplied to this zone, and may with or somewhat lower than that employed in the residuum heating coil may be utilized, when desired.

As an example of one specific operation of the process as it may be conducted in an apparatus, such as illustrated and above described; the charging stock, which comprises a mixed base crude of about 35 A. P. I. gravity, containing approximately 25% of good quality gasoline fractions boiling up to approximately 400 F. is heated at substantially atmospheric pressure to a temperature of approximately 650 F. and separated into vaporous and liquid components. Said liquid components are passed through a heating coil wherein they are heated to an outlet conversion temperature of approximately 940 F. and are thence passed through an enlarged reaction chamber maintained at a superatmospheric pressure of approximately 300 pounds per square inch. Both vaporous and liquid conversion products are discharged from the reaction chamber in commingled state and introduced into a separating chamber maintained at a superatmospheric pressure of approximately pounds per square inch. Residual liquid is withdrawn from the separating chamber and quickly heated in a separate heating coil to an outlet temperature of approximately 950 F., the resulting heated products being introduced into alternately operated coking chambers maintained at a superatmospheric pressure of approximately pounds per square inch, wherein their high-boiling components are reduced to coke. vaporous products from the coking chamber are supplied to said separating chamber wherein entrained and/or dissolved high coke-forming materials are separated therefrom and commin'gled with said residual liquid. vaporous products from the separating chamber are subjected to fractionation together with the low-boiling vaporous components of the charging stock removed from the distilling steps. Reflux condensate from the fractionating step is returned to the first mentioned heating co-il for further cracking, the fractionated vapors being subjected to condensation and the resulting distillate, which comprises a mixture of straight-run and cracked gasoline is recovered. This operation will yield a barrel of crude charging stock approximately 73% of 400 F. end-boiling point gasoline of good quality and approximately 58 pounds of good quality petroleum coke, the remainder being chargeable principally to incondensible gas.

I claim as my invention:

A conversion process which comprises partially vaporizing a hydrocarbon charging oil of relatively wide boiling range thereby forming vapors and unvaporized oil, subjecting the latter to cracking conditions of temperature and pressure in a heating coil and separating the resultant products into vapors and residual liquid in a separating chamber, heating residual liquid from said chamber to conversion temperature in a second heating coil and reducing the same to coke in a coking chamber apart from said separating chamber, introducing, the vaporous products from the coking chamber into said separating chamber and therein separating from said vaporous products the heavy pitch-like and tarry materials contained therein as a. result of the coking operation, such materials being returned tosaid second coil in the residual liquid supplied to this coil from the separating chamber, combining the vapors evolved from the charging oil by said partial vaporization with the vapors separated in the separating chamber, fractionatin'g the commingled vapors to condense heavier fractions thereof, supplying separate portions of the resultant reflux condensate to said heating coils, and finally condensing the fractionated vapors.

JEAN DELATTRE SEGUY. 

